A reliable sump pump can keep your basement dry, but what happens when the power goes out during a storm? Installing a battery-operated backup sump pump provides an extra layer of protection for your home. This system ensures your basement stays dry even during power outages or if your primary pump fails. We’ll guide you through the process of installing a battery-operated backup sump pump. In the video above, This Old House plumbing and heating expert Richard Trethewey demonstrates the installation process to help you keep your basement dry even when the lights are out.

How Do Battery-Operated Backup Sump Pumps Work?

Battery-operated backup sump pumps are designed to work in tandem with your primary electric sump pump. They provide an additional safeguard against basement flooding when your main pump can’t operate due to power outages or mechanical failures. These systems typically consist of a 12-volt pump, a deep-cycle marine battery, and a battery charger.

When the water level in your sump pit rises above a certain point, the backup pump’s float switch activates, turning on the pump. The pump then draws power from the battery to remove water from the pit, even when there’s no electricity. This system keeps your basement protected during power outages or if your primary pump fails.

Preparing for Sump Pump Backup Installation

Before you begin the installation process, gather all necessary materials and tools and your sump pump. Sump pumps with battery backups cost between $100 and $1,000, according to Angi.  

Tools and Materials Needed

To install a battery-operated backup sump pump, you’ll need the following:

• Battery box
• Battery-operated backup sump pump kit
• Check valve
• Deep-cycle 12-volt marine battery
• Handsaw
• PVC cement
• PVC pipe and fittings
• Stainless steel hose clamps
• Screwdriver
• Teflon tape
• Utility knife

Choosing the Right Backup Pump

When selecting a battery-operated backup sump pump, consider the following factors:

• Pumping capacity (gallons per hour): Choose a backup sump pump with enough capacity to handle the volume of water that may accumulate during storms or power outages. Higher pumping capacity ensures better protection against flooding in your basement. With a fully charged battery, battery-operated sump pumps typically have a pumping capacity of 800–2,000 GPH.
• Battery life: Battery-operated sump pumps rely on backup power, so consider the lifespan of the battery. Look for a pump with a long-lasting battery to provide peace of mind during extended power outages. A new or fully charged battery can last up to 7 or 8 hours.
• Alarm features: Many backup sump pumps come with built-in alarms that notify you when the pump is activated or when the battery is low. These alerts can help you take timely action to prevent water damage.
• Compatibility with your existing system: Ensure that the backup sump pump you choose is compatible with your current sump pump system to avoid installation issues. Some systems may require specific models or components for seamless integration.

Step-by-Step Battery-Operated Backup Sump Pump Installation Process

Installing a battery-operated backup sump pump is a moderately challenging DIY project that can typically be completed in 2 to 4 hours. Follow these steps for proper installation.

Removing the Existing Pump

Begin by unplugging the existing sump pump and disconnecting it from the discharge pipe. Remove any clamps or fittings securing the pump, then lift it out of the sump pit. Inspect the pit for any debris or damage that might affect the new installation.

Installing the New Primary and Backup Pumps

Apply Teflon tape to the threads of a check valve, then attach it to the side of the new primary pump. Next, wrap Teflon tape around the threads of the battery-powered pump and connect it to the check valve. Carefully lower both pumps into the sump pit.

Connecting the Discharge Pipe

Cut 1-1/2-inch-diameter PVC pipe to the appropriate length for your discharge pipe. Use PVC cement to glue the pipe and fittings together, creating a configuration that aligns with your existing discharge pipe. Connect the new pipe to the existing one using stainless steel hose clamps and a rubber connector.

Setting Up the Battery and Charger

Place the deep-cycle 12-volt marine battery into a protective plastic box. Position the box on a nearby shelf or elevated surface to keep it away from potential water exposure. Connect the battery charger to ensure the battery remains fully charged and ready for use.

Making Electrical Connections

Carefully make the low-voltage cable connections between the battery and the backup pump, following the manufacturer’s instructions. Plug the battery charger and the power cord for the primary sump pump into a 110-volt electrical outlet.

Testing the System

To test the primary pump, reach into the sump pit and lift the float valve until the pump activates. Repeat this process for the battery-powered backup pump to ensure both systems are functioning correctly. In the video, Trethewey demonstrates how the backup pump activates when the primary pump fails, complete with an audible alarm to alert homeowners.

Maintenance and Care for a Battery-Operated Backup Sump Pumps

Regular maintenance keeps your battery-operated backup sump pump in good working condition and ready to protect your basement when needed.

Battery Maintenance

Check the battery’s water levels monthly and top off with distilled water if necessary. Clean the battery terminals regularly to prevent corrosion. Replace the battery every three to five years or as recommended by the manufacturer.

System Testing

Test your backup sump pump system at least once every three months. Here’s how:

1. Unplug the primary pump.
2. Fill the sump pit with water.
3. Ensure the backup pump activates and removes water efficiently.
4. Check that the alarm system functions properly.

Pump Inspection

Regularly inspect both the primary and backup pumps for signs of wear or damage. Clean the pumps and remove any debris from the sump pit to prevent clogs.